“Prolonged sitting is a common behavior in modern society with commuting, work and domestic settings that prompt us to sit,” said lead study author Michael Wheeler of Baker Heart and Diabetes Institute in Melbourne, Australia.

Recent studies have shown that extended sitting during the day can increase blood pressure, which is a key risk factor for heart disease.

“Older adults, in particular, can accumulate lots of sitting throughout the day, with upwards of two-thirds of their day devoted to sedentary behaviors,” he told Reuters Health by email.

Although both exercise and breaks in sitting can reduce high blood pressure, or hypertension, Wheeler and colleagues analyzed whether a combination of exercise and short breaks would offer further benefits.

They recruited 67 men and women who were between 60 and 74 years old and overweight or obese. About 4 in 10 participants also had high blood pressure. Every participant completed three different day-long tests in random order, each separated by a minimum of six days. Researchers measured heart rate, blood pressure, blood sugar and other blood markers during each test condition.

In one condition, participants sat uninterrupted for eight hours. In another, they sat for an hour, then walked at moderate intensity for 30 minutes on a treadmill, and sat for the next 6.5 hours. In the third condition, they sat for an hour, did 30 minutes on the treadmill, then returned to sitting, but also did 3-minute walking breaks on the treadmill every 30 minutes for the rest of the day. The treadmill was set at two miles per hour during the exercise bouts, with an incline for the 30-minute morning walking program and no incline for the 3-minute walking breaks.

During the sitting periods in the study, participants were instructed to read or work quietly on a laptop and avoid activities that may raise blood pressure, such as watching television and making nonessential phone calls.

Overall, the research team found that participants, as a group, had lower average blood pressure, by about 1 mm/Hg, across the day when they were in a test condition that included exercise. The biggest reduction was seen when people did the 30-minute treadmill exercise in the morning and took 3-minute walking breaks throughout the day – although the additional benefit of the walking breaks was seen only among women.

Women also had lower blood levels of epinephrine, a hormone that raises blood pressure, when they were in either test condition that included exercise.

“We were surprised by the fact that only women demonstrated an additional reduction in blood pressure when exercise was followed by breaks in sitting,” Wheeler said.

Future studies may add another condition that looks at sex differences in blood pressure response alone, he said.

“Sex differences seem to be an emerging line of study when it comes to blood pressure changes and cardiometabolic risk factors,” said Dharini Bhammer of the University of Nevada, Las Vegas, who wasn’t involved in the study.

Upcoming research will look at specific vascular function and glucose regulation for men and women aiming to reduce their blood pressure, she said, as well as the ideal timing and duration of sitting breaks and exercise that will help the most.

“We recognize that exercise is good, and we now have the awareness that prolonged sitting can increase blood pressure,” Bhammer told Reuters Health in a phone interview. “Now we need to build breaks into our routines as a default so we’re not sitting for four hours at a time.”